Remove battery isolator with new smart charger?

[cwiert]

Hi. I have a 1998 400DB that I just replaced the old original battery charger with a new 3-bank smart charger (ProMariner 1240P).

I have 5 batteries and 3 banks:
Bank 1 - Port engine and port house get 2 batteries wired together
Bank 2 - Stbd engine and stbd house get 2 batteries wired together
Bank 3 - Genny gets 1 battery all to itself

Both of my stbd batteries were bad (I had them all tested with a proper battery tester that tests CCAs, etc). I had to use the "Emergency start" switch to get the stbd engines running. I have replaced those with new ones.

Now, I'm having issues with the previously good port batteries. I had to use the emergency start to start the port engine where 1 week ago, those were my "good batteries."

This leads me to believe that maybe the original, old, isolator needs to go. My friend Bill, ZZ13, informed me that Sea Ray stopped using these isolators after 1998 when the converter no longer required it. So could that old isolator be messing up the "smart" aspect of my new charger?

 

[PMC]

How many charging banks did the original charger support? Was it a single output running through the isolator to the 3 banks?

 

[cwiert]

How many charging banks did the original charger support? Was it a single output running through the isolator to the 3 banks?

no, it was a 3 bank charger also. it was plug and play. all I had to do was swap the wires from the old to the new.
I guess what I'm still unclear on is what the isolator actually does, and why was it needed with the old charger and not the new one.

 

[cwiert]

Here's the old setup. Charger and isolator.

Sent from my iPhone using Tapatalk

 

[PMC]

I looked up the DC wiring document (supplemental owners manual), and that isolator is used to charge the batteries from either engine alternator. See attached image

 

[JimG]

no, it was a 3 bank charger also. it was plug and play. all I had to do was swap the wires from the old to the new.
I guess what I'm still unclear on is what the isolator actually does, and why was it needed with the old charger and not the new one.

The isolator is there to keep one bank from trying to equalize (or charge) the other. Normally used when there is only one charge source. Although as Paul points out, two charge sources can charge both banks.

I would think that with the new ProMariner charger, you wouldn't need the isolator.

 

[ZZ13]

The isolator is there to keep one bank from trying to equalize (or charge) the other. Normally used when there is only one charge source. Although as Paul points out, two charge sources can charge both banks.

I would think that with the new ProMariner charger, you wouldn't need the isolator.

I contacted Sea Ray on this very subject about a year ago when I discovered my DC wiring did not match the diagram for the 2001 400DB that Paul posted. My boat has no battery isolator. They then sent me the appropriate diagram, which also comes with all the 2002 documentation. And they explained the isolator was removed from the design of my 2001 boat because the battery charger no longer required it. As a side note, one thing I have discovered is the best documentation for the 2001 400DB is actually the 2002 documentation (supplemental manual and parts list). They are spot on to the 2001 400DB. The 2001 documentation is lagging in updates and contains 2000 and earlier descriptions.

 

[ZZ13]

Here is the newer wiring diagram without the isolator:

 

[Creekwood]

I suggest you check the wiring on the boat first. I also replaced my OEM Promariner 30A charger with a new Pronautic 1240P. What I did not realize until later that summer was that the fusing in the OEM setup uses 30amp delay fuses between the charger and the batteries. The new Pronautic charges have the ability to direct 100% of the 40 amps to a single bank that is run down.

So what happened is that after a long weekend on the hook, my house bank (2 6v golf cart batteries) was drawn way down. After a short run back to the dock, once on the shore power, the charger ramped up to the full 40 amps to that bank, actually overheating the fuse holder and then blowing the fuse. I did not notice at the time since the house bank was not used for much while at the dock, but it stayed discharged. The next time I used it, it turned over slowly, but started, so I just thought that maybe those batteries were getting old. It turns out that they were only getting charged when running the engines, not by the charger, due to the blown fuse. Once I figured that out, I realized I needed to upgrade the wiring and fuses from the charger to the battery switch on the boat. All is well now.

Bottom line, check your fuses and wiring before you replace the isolator

 

[ttmott]

My boat did not have isolators also and doesn't need them. When I updated the system with an inverter and higher capacity alternators I also added ACR's between the three banks. This is "belts and suspenders" in the event one of the charger legs are lost or one of the three alternators drop out. Having the ACR's makes the system very robust for very low cost.

 

[cwiert]

Thanks for the replies. I will check the fuses. Also, it appears that the isolator and charger have nothing to do with each other, correct? It seems the isolator is only related to the engines alternators. Is that accurate?

 

[ttmott]

Not really, the isolators allow the charging means for one bank (alternator or charger) to charge another bank.

 

[Wylie_Tunes]

So the charger is going through the diode ISO? I wouldnt want that at all. Why induce a .7V drop into what should be recharging and maintaining the batteries. The ISO doesnt need to go, but the charger should be battery direct.

 

[ZZ13]

So the charger is going through the diode ISO? I wouldnt want that at all. Why induce a .7V drop into what should be recharging and maintaining the batteries. The ISO doesnt need to go, but the charger should be battery direct.

I don't think it is. If you look at the diagram in post #5, the charger goes direct to each battery bank with the post on the isolator essentially just acting as a connection lug for that path.

 

[Mike Blake]

A battery isolator is an electrical device that divides direct current (DC) into multiple branches and only allows current in one direction in each branch. The primary benefit of such an arrangement is the ability to simultaneously charge more than one battery from a single power source (e.g., an alternator) without connecting the battery terminals together in parallel.